1. Field of the Invention
The present invention relates to liquid sprinkler assemblies and more particularly to liquid sprinklers which rotate through a selected arcuate path in response to the impact of a liquid stream upon stream-intersecting surfaces.
2. Discussion of the Technical Problem
It is known to drive a rotatable liquid sprinkler by providing a stream-intersecting surface which is impacted upon by the emitted liquid stream. Examples of such devices include those taught in U.S. Pat. Nos. 2,256,737; 2,710,226; 3,022,012; 3,193,203; 3,350,015; 3,408,099; 3,434,665; 3,581,994; 3,764,073; 3,765,608; 3,779,462; 3,837,576; 3,841,563; 3,918,643; 3,924,809; 3,930,617; 3,952,953; 3,977,610; 4,055,304; 4,153,202; 4,173,306; 4,195,782; 4,216,913; 4,234,126; and 4,235,379. Commonly the stream-intersecting surface oscillates into and out of the discharge stream of liquid and impact energy is temporarily stored in a spring to rotate the assembly about an axis and return the stream-intersecting surface into the discharge stream.
Difficulties with such devices are encountered, however, because satisfactory control over the direction of fluid discharge has been largely unattainable heretofore. While the arc of rotation of the sprinkler facility has been largely controllable through mechanical means, there nevertheless exists a need for improved control over the direction of fluid discharge, because of the flow disruption created by the stream-intersecting surface.
Additionally, it is desirable to fabricate a sprinkler assembly from plastic components, preferably having a design which permits the use of open-and-shut injection molding techniques for production economy. In this regard U.S. Pat. No. 3,977,610 is of interest. This patent discloses an oscillating sprinkler which includes a pivotable arm having a pair of concave stream-impacting vanes which are spaced relative to one another such that they overlap neither laterally nor longitudinally relative to the original direction of fluid discharge. The vane closest to the discharge unit directs the fluid stream toward the more distant of the vanes.
A pivotable arm having such vanes may conveniently be formed of plastic by open-and-shut injection molding techniques, in that a lateral opening between the pair of vanes exists due to the lack of overlap therebetween which facilitates separation of the mold parts. However, control over the direction of fluid discharge has been found to be unsatisfactory because a portion of the fluid stream undesirably exits through the lateral opening between the vanes rather than continuing in the desired direction. It can be appreciated that this condition wastes water and may create substantial inconveniences by dispersing water onto undesirable areas. Thus there exists a need in the art for a method of controlling the direction of fluid dispersal from an impulse sprinkler, particularly in conjunction with the use of relatively inexpensive plastic components which may be formed by open-and-shut injection molding techniques.